Multi-chamber container

ABSTRACT

A multi-chamber container having chambers formed of a film of which at least an innermost layer is a cyclic polyolefin, one chamber being partitioned from another chamber by a partition wall, and the partition wall having an easily peelable seal layer which contains a low-density polyethylene and a propylene/α-olefin copolymer. The multi-chamber container enables the contents of the chambers to be mixed together.

TECHNICAL FIELD

This invention relates to a multi-chamber container having a plurality of chambers separated by a partition wall having a peelable seal layer (so-called easily peelable seal layer) and, particularly, to a multi-layered container having a plurality of chambers for medical use. More specifically, the invention relates to a multi-chamber container which enables the contents contained in a plurality of chambers to be mixed together by causing the plurality of chambers to communicate with each other upon peeling off of the partition wall having an easily peelable seal layer.

BACKGROUND ART

Usually, a multi-chamber container having a plurality of small chambers for separately containing liquid agents, powder agents or solid agents has heretofore been formed by using a flexible plastic film. One chamber of a plurality of chambers is partitioned from another adjacent chamber by a partitioning wall that allows communication. The partitioning wall is such that the inner surfaces of the film forming the small chambers are directly melt-adhered together, or are melt-adhered together via an insert film held between the inner surfaces. The partitioning wall easily peels off when an external pressure is applied to the surface of the chambers containing the contents; i.e., interiors of the plurality of chambers communicate to allow the contents contained therein to be mixed together.

As the plastic film (which includes sheet) for forming plural chambers, there has been used a two-layer film including an inner layer of a mixed resin of a straight-chain low-density polyethylene (LLDPE) and a polypropylene (PP) and an outer layer of the straight-chain low-density polyethylene (LLDPE), or a three-layer film including an inner layer of the straight-chain low-density polyethylene (LLDPE) and the polypropylene (PP), an intermediate layer of a mixed resin of the straight-chain low-density polyethylene (LLDPE) and an ethylene/α-olefin elastomer, and an outer layer of the straight-chain low-density polyethylene (LLDPE) (Japanese Patent No. 3060132, Japanese Patent No. 3079403, etc.). In these multi-layered films, the inner layers of the mixed resin of the straight-chain low-density polyethylene (LLDPE) and the polypropylene (PP) are sealed at a melt-adhesion temperature of about 110 to 130° C. to form an easily peelable seal layer, and are further sealed at a melt-adhesion temperature of about 170 to 200° C. to form a strongly melt-adhered layer.

As the plastic film for forming plural chambers, further, there have been used an aluminum foil laminate (three-layer film of polyester/aluminum foil/polyethylene), a laminated film including a silica-deposited layer (PE/SiO₂/PET/SiO₂/PE) and a polyethylene tubular film (U.S. Pat. No. 5,865,309, U.S. Pat. No. 5,706,937, JP-A-2003-104391). The multi-chamber container is formed of a chamber of the aluminum foil laminate overlaid on the laminated film including the silica-deposited layer, and a chamber of the polyethylene tubular film. The plurality of such chambers are melt-adhered together via a film forming a weakly melt-adhered portion of a polymer blend of a polyethylene and a polypropylene held between the inner surfaces of the polyethylene.

As the weakly melt-adhered portion, a resin having small melt-adhering strength to the polyethylene which is the material forming the innermost layer, for instance, a blend of a polyethylene and a resin with no compatibility thereto, is conventionally used.

In the multi-chamber container, on the other hand, there arise such problems as a decrease in the medicament content, an increase of medicament analogues, an increased turbidity of the medicament solution and formation of insoluble fine particles which are generated by interaction of the medicine which is an effective component with impurities such as low-molecular components eluted from the linear polyolefin and components eluted from the adhesive layer.

Under such circumstances, the present inventors have already proposed a multi-layered multi-chamber container for medical use which is formed by a multi-layered film including an innermost layer of a cyclic polyolefin or a polymer blend containing the cyclic polyolefin and a second layer of a linear polyolefin adjacent to the above layer (US 2006/0035044). The multi-layered multi-chamber container can be subjected to γ-ray sterilization, decreases the low-molecular components and adhesive components that are eluted out from the multi-layered container to eliminate the above-noted problems.

DISCLOSURE OF THE INVENTION

The present invention provides a seal layer (easily peelable seal layer) used for a multi-chamber container of which at least one chamber chiefly uses a layer of a cyclic polyolefin as an innermost layer, the seal layer being strongly melt-adhered to the innermost layer of the cyclic polyolefin and being allowed to be peeled off from the layer of the cyclic polyolefin so that the contents in the plurality of chambers in the container can be mixed together at the time of use.

The present invention relates to a multi-chamber container having chambers of which at least the innermost layer is made of a film of a cyclic polyolefin, wherein one chamber and another chamber are partitioned by partition walls, and the partition walls have an easily peelable seal layer containing a low-density polyethylene and a propylene/α-olefin copolymer.

In this invention, the cyclic polyolefin layer as the innermost layer is amorphous and cannot be weakly melt-adhered to another layer. To impart easily peelable property to a layer, it is conventional to obtain an easily peelable layer by blending the same material as a container body with a different material. When the cyclic polyolefin is used for the container body, however, the container body and the sheet made of cyclic polyolefin blended with a material different from the cyclic polyolefin often fail to exhibit an easily peelable property or lose the easily peelable property after being stored for extended periods of time. The present invention uses a sheet made of a blend comprising different materials from the cyclic polyolefin, particularly, a blend of a low-density polyethylene and a propylene/α-olefin copolymer to realize an easily peelable property that enables the contents in the container to be mixed together at the time of use while maintaining the seal strength for extended periods of time.

In the present invention, the multi-chamber container is a container having a plurality of chambers, one chamber being partitioned from another chamber by a partition wall. A specific example may be a container in which a liquid agent container containing a liquid agent and a medicament container liquid-tightly containing a medicament are partitioned from each other by the partition wall having an easily peelable seal layer. For example, the container has a pair of partition walls facing the ends on one of the two chambers, an end of the other chamber being inserted and melt-adhered between the above partition walls, and the two chambers being partitioned by the partition walls.

In this invention, at least one of the chambers of the multi-chamber container is formed by a single or multi-layered film in which at least the innermost layer is a cyclic polyolefin. Usually, the chambers separately contain a liquid agent, powdery agent or solid agent. The shape and size of the container may be different depending upon the contents. Other of the chambers of the multi-chamber container may be formed by a single or multi-layered film in which the innermost layer is not a cyclic polyolefin.

In the present invention, the film that constitutes at least one chamber is a single-layer film or a multi-layered film having at least an innermost layer of the cyclic polyolefin. Preferably, it is a multi-layered film comprising a first layer of the cyclic polyolefin as the innermost layer and a second layer of a linear polyolefin adjacent to the first layer.

The cyclic polyolefin is a thermoplastic saturated norbornene-type polymer which is known (JP-A-4-276253, JP-A-5-317411, JP-A-8-155007, etc.). Specific examples thereof include polymers having structural units represented by the following chemical formula 1 and/or chemical formula 2.

wherein R₁ and R₂ each represent a hydrogen atom or a hydrocarbon residue having 1 to 10 carbon atoms and may be the same or different, and R₁ and R₂ together may form a ring, and n is a positive integer.

wherein R₃ and R₄ each represent a hydrogen atom or a hydrocarbon residue having 1 to 5 carbon atoms and may be the same or different, and R₃ and R₄ together may form a ring, l and m are positive integers, and p is 0 or a positive integer.

The polymer having a structural unit represented by chemical formula 1 is a saturated polymer obtained from a ring-open polymer which is obtained by ring-opening polymerizing a monomer, for example, 2-norbornene and alkyl and/or alkylidene substituted derivatives thereof, such as 5-methyl-2-norbornene, 5,5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene, 5-ethylidene-2-norbornene; dicyclopentadiene, 2,3-dihydrodicyclopentadiene and derivatives thereof substituted with alkyl such as methyl, ethyl, propyl or butyl; dimethano-octahydronaphthalene and alkyl and/or alkylidene substituted derivatives thereof, such as 6-methyl-1,4:5,8-dimethano-1,4,4a,5, 6,7, 8,8a-octahydronaphthalene, 6-ethyl-1,4:5,8-dimethano-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-ethylidene-1,4:5,8-dimethano-1,4,4a,5,6,7,8,8a-octahydronaphthalene; a trimer or tetramer of cyclopentadiene, such as 4,9:5,8-dimethano-3a,4,4a-5,8,8a,9,9a-octahydro-1H-benzoindene, 5,8-methano-3a,4,4a,5,8,8a,9,9a-octahydro-1H-benzoindene, 5,8-methano-1,4,4a,4b,5,8,8a,9b-octahydro-1H-fluorene, and 4,11:5,10:6,9-trimethano-3a,4,4a,5,5a,6,9,9a,10,10a,11,11a-dodecahydro-1H-cyclopentaanthracene, and hydrogenating the ring-opened polymer by an ordinarily employed hydrogenation method.

The polymer having a structural unit represented by the chemical formula 2 is a saturated polymer obtained by copolymerizing the above norbornene-type monomer and ethylene according to a known method, and/or a hydrogenated product thereof.

The cyclic polyolefin used in the present invention may be one in which the thermoplastic saturated norbornene-type polymer is a hydrogenated product of a ring-opened polymer of a polar monomer, a copolymer of the above norbornene-type monomer and ethylene, or a hydrogenated product of the above copolymer.

The layer composed of the cyclic polyolefin has a thickness of, usually, 3 to 5000 μm, preferably, 5 to 2000 μm and, when used as a multi-chamber container for medical use, has a thickness of, usually, 10 to 500 μm and, preferably, 20 to 300 μm.

As the second layer composed of the linear polyolefin adjacent to the first layer, there can be exemplified a layer of a linear polyolefin such as low-density polyethylene, straight-chain low-density polyethylene, medium-density polyethylene, high-density polyethylene, polypropylene, or propylene/α-olefin copolymer. The layer of the linear polyolefin has a thickness of, usually, 3 to 5000 μm, preferably, 5 to 2000 μm and, when used as a multi-chamber container for medical use, has a thickness of, usually, 10 to 500 μm and, preferably, 20 to 300 μm.

The film constituting the chambers, as required, further includes a gas-barrier layer and/or a printable layer on the second layer of the linear polyolefin. The printable layer is one on which a medium such as a printing ink can be printed for displaying characters or patterns on the surface of the container. The gas-barrier layer is a layer for preventing the passage of moisture or gases. The printable layer in this invention is, for example, a polyester layer such as polyethylene terephthalate or a polyester layer on which an inorganic matter such as silica is deposited. The gas-barrier layer is, specifically, a metal foil, a metal-deposited layer or an inorganic material-deposited layer. The metal foil may be, for example, an aluminum foil. As the metal-deposited layer, there can be exemplified an alumina-deposited polyester film or a nylon film. The inorganic material-deposited layer may be a silica-deposited polyester film.

In the present invention, the films forming the chambers have been adhered together by the easily peelable seal layer. The easily peelable seal layer means a layer that can be easily peeled off at the time of preparing a medicine. Usually, the easily peelable seal layer easily peels when an external pressure is applied to the surface of one of chambers containing the contents, enabling the interiors of the plurality of chambers to communicate with each other and the contents in the containers to be mixed together.

The partition wall for partitioning the chambers in the present invention provides a weakly melt-adhered seal portion formed of the above-mentioned easily peeling seal layer and a strongly melt-adhered seal portion.

The weakly melt-adhered seal portion in the present invention is the easily peelable seal layer which is a composition containing the low-density polyethylene and the propylene/α-olefin copolymer.

In the present invention, the low-density polyethylene may be a low-density polyethylene obtained by polymerizing an ethylene monomer in a high-pressure radical polymerization method using a radical initiator such as an organic peroxide. The low-density polyethylene is a low-density polyethylene having a melt flow rate (MFR) in a range of 0.5 to 8.0 g/10 min. and a density of 0.900 to 0.930. Examples thereof include “Petrothene” manufactured by Toso Co., “Novatec” manufactured by Japan Polyethylene Co., “Excellen” manufactured by Sumitomo Kagaku Co., “UBE Polyethylene” manufactured by Ube-Maruzen Polyethylene Co., and “Mirason” manufactured by Prime Polymer Co. As the α-olefin in the propylene/α-olefin copolymer of the present invention, further, there can be used an α-olefin having 2 or 4 to 8 carbon atoms or, specifically, ethylene, butene, pentene, hexene, heptene, octene or two or more of them. That is, the propylene/α-olefin copolymer of the present invention may specifically be a dicopolymer such as propylene/ethylene copolymer or propylene/butene copolymer, or a tercopolymer such as propylene/ethylene/butene copolymer. The propylene/α-olefin copolymer of the present invention has a melting point in a range of, for example, 100° C. to 150° C. As the propylene/α-olefin copolymers that have now been placed on the market, there can be exemplified “Novatec PP” and “Wintec” manufactured by Japan Polyethylene Co., “Excellen” manufactured by Sumitomo Kagaku Co., and polypropylenes manufactured by San Alomer Co. and Prime Polymer Co.

It is desired that the mixing ratio by weight of the low-density polyethylene and the propylene/α-olefin copolymer be 80:20 to 20:80, more preferably, 75:25 to 25:75 and, most preferably, 70:30 to 30:70. When the amount of the low-density polyethylene exceeds 80% by weight, the weakly melt-adhered seal that is formed by the film is too strong. When the amount thereof is less than 20% by weight, the weakly-adhered seal strength loses stability.

The partition wall (also called an easily peelable sheet or seal layer) of the invention is prepared from a mixture of a low-density polyethylene and a propylene/α-olefin copolymer in the usual manner. Though there is no particular limitation on the method for forming the mixture, there is preferably used a method for dry-blending resin pellets in advance or a melt-blending method using a biaxial extruder.

In order to improve gas-barrier properties, easily peelable properties and mechanical properties, the easily peelable sheet of the present invention may be a laminated film having the easily peelable seal layer as at least one surface layer and another resin layer thereon. The number of said easily peelable seal layer and other resin layers is suitably selected depending upon use. Specifically, other resins are thermoplastic resins such as straight-chain low-density polyethylene resins and cyclic polyolefin-type resins, or a mixture of these resins.

The easily peelable sheet of the present invention can be produced in the form of a sheet by a molding method that is used for general thermoplastic resins, such as T-die molding or inflation molding. Further, the easily peelable laminated-layer sheet can be produced by co-extrusion molding, dry lamination or extrusion coating.

It is desired that the easily peelable sheet of the present invention obtained by the above methods has a thickness of about 5 to about 500 μm and, more preferably, 20 to 400 μm. When the thickness is less than 5 μm, the strength of the film becomes insufficient and it becomes difficult to form an excellent easily peelable seal layer. When the thickness is greater than 500 μm, on the other hand, the flexibility of the film decreases and it becomes difficult to melt-adhere the film.

The easily peelable laminated sheet of the present invention has a thickness of 10 to 500 μm and, preferably, 20 to 400 μm. In the above sheet, the portion occupied by the sheet having the easily peelable property is not smaller than 5% and, preferably, not smaller than 10% of the thickness of the sheet as a whole. When the portion is not larger than 5%, the peeling strength of the easily peelable seal layer formed by the sheet decreases.

In the present invention, strong melt-adhesion means an adhesion formed by heat-melting and adhering the films forming the chambers to liquid-tightly contain the contents therein and which cannot be peeled off by pressure exerted on the external side of the chamber. To strongly melt-adhere the layers of the cyclic polyolefin forming the innermost layer of the present invention, the melt-adhesion is accomplished, for example, at 150 to 200° C. for 1 to 3 seconds under a pressure of 0.2 to 0.5 MPa. To maintain the quality, for example, to guarantee the product for three years, it is desired to maintain a T-peel strength of not smaller than 20 N/15 mm after being maintained at 60° C. for 7 weeks.

When it is necessary to guarantee the quality of a product sterilized with radioactive rays for 3 years, the strength at 60° C. for 7 weeks (=49 days) is conducted in compliance with Guidelines for Industrial Radiation Sterilization of Disposable Medical Products (IAEA: TEC DOC-539 (1990)) to confirm the effect in short periods of time. T-peel strength for 7 days at 60° C. is equivalent to that for 180 days under room temperature.

In the present invention, the weak melt-adhesion is an adhesion such that the partition wall adheres together or the partition wall adheres to the innermost layers of the films forming the chambers, and can be easily peeled off at the time of preparing a medicine. The partition wall comprising a blend of the low-density polyethylene and the propylene/α-olefin copolymer is weakly melt-adhered together, or the partition wall is weakly melt-adhered to the layer of the cyclic polyolefin, for example, at 130 to 170° C. for 0.5 to 2 seconds under a pressure of 0.1 to 0.3 MPa. To maintain the quality of weakly melt-adhered seal strength, for example, it is desired that a T-peel strength is in a range of 0.5 to 3 N/15 mm after being kept at 60° C. for 7 weeks.

There is no particular limitation on the method for forming the easily peelable seal layer of the present invention, and there can be used any conventional method for making an easily peelable seal layer. Namely, there can be exemplified the following methods.

1) A small piece of film constituting an easily peelable seal layer is strongly melt-adhered onto the innermost layer of cyclic polyolefin of one film, and then, the innermost layer of cyclic polyolefin of another film is weakly melt-adhered onto the above small piece of film.

2) A small piece of film constituting the easily peelable seal layer is inserted between two films having the innermost layers of cyclic polyolefin, and a temperature differential is imparted to metal molds, so that a strong melt-adhesion is accomplished on the side of one film and a weak melt-adhesion is accomplished on the side of the other film.

3) The small piece of film constituting the easily peelable seal layer is weakly melt-adhered onto the innermost layer of cyclic polyolefin of one film, and then, the other film is strongly melt-adhered onto the above small piece of film.

There is no particular limitation on the method for producing the chambers of the multi-chamber container of the present invention, and there can be employed any conventional method concerning with the formation of such chambers. Namely, there can be exemplified the following methods.

1) Two films are overlaid back and front. A film constituting the easily peelable seal layer is held between the two films at a portion slightly above the lowermost end of the films and both the right and left side portions of the two films, except the lower ends thereof, are strongly melt-adhered together so as not to be peeled off. Next, the easily peelable seal layer is weakly melt-adhered to the innermost layers of the films. Thus, the upper sides of the two films form a bag that has an opening upward, and the lower end portions thereof become a pair of connecting piece portions facing each other. The connecting piece portions are opened on both the right and left sides and downward. The two films are weakly melt-adhered to the lower ends of the film constituting the easily peelable seal layer to thereby form a partition portion (weakly melt-adhered seal portion), and the two films are strongly melt-adhered on both the right and left sides so as not to be peeled off.

Thus, there is formed a bag with the upper sides of the two films opening upward and the lower ends thereof forming a pair of connecting pieces facing each other. The connecting piece portions are opened on both the right and left sides and downward. The bag is filled with the medicine, and the upper portions of the two films are strongly melt-adhered together so as not to be peeled off to thereby form a chamber (see U.S. Pat. No. 5,865,309, FIG. 1A to 1D, JP-A-2003-104391, FIG. 3).

2) A film constituting an easily peelable seal layer is inserted in an upper end of a tube that is opened at both ends, the tube is weakly melt-adhered to the film constituting the easily peelable seal layer to thereby form a partition portion (weakly melt-adhered seal portion), and the front and back wall portions of the tube are strongly melt-adhered so as not to be peeled off on both the right and left sides thereof. Subsequently, a connection port is inserted in the lower end of the tube and is strongly melt-adhered together so as not to be peeled off, and the remaining opening portion at the lower end of the tube is strongly melt-adhered together so as not to be peeled off.

Next, the small chamber is filled with a liquid through the connection port which is, then, closed with a plug to form a second small chamber (see U.S. Pat. No. 5,865,309, FIG. 2A to 2D, JP-A-2003-104391, FIG. 5).

There is no particular limitation on the method for connecting the chambers of the present invention prepared as described above, and any widely known production method related to making such chambers can be employed. Namely, the following method can be exemplified.

The two connecting piece portions of the first chamber are widely opened downward, the upper end of the second chamber is inserted in between the two connecting piece portions from the lower side, which are, then, heat-melt-adhered together to connect the two small chambers integrally together (see, U.S. Pat. No. 5,865,309, FIG. 3 and 4, JP-A-2003-104391, FIG. 6).

U.S. Pat. No. 5,865,309 is incorporated herein in its entirety by reference.

The present invention will now be specifically described by way of Examples.

In the Examples, the T-peel strength is measured using a universal (Instron) tester by spreading both ends of two pieces of films over 180° and holding their ends using chucks that are installed to peel. In this state, one end is pulled upward to measure the force applied to peel the melt-adhered portion. The strength of weak seal is set variously depending upon the size of the container or the state in which it is used. In the case of, for example, a 100-mL container for infusion, the strength of the weak seal for the peeling operation may suitably be 0.5 to 3 N/15 mm.

EXAMPLES 1 TO 3

A cyclic polyolefin (trade name: Zeonor manufactured by Zeon Corp.) was extruded at 250° C. to make a film A (60 μm). On this film A (100 mm×155 mm), a small piece of film made of a blend of a low-density polyethylene (density: 0.922 g/cm³, trade name: Petrothene manufactured by Toso Co.) and a propylene/α-olefin copolymer (Tm 135° C., trade name: Novatec PP manufactured by Japan Polypropylene Co.) (weight ratios of mixture, 70/30, 50/50, 30/70, 6.0 mm×30 mm) was placed, and was strongly melt-adhered thereto for 2 seconds using a metal mold heated to a temperature of 180° C. Next, on the above small piece of film, another cyclic polyolefin film B (100 mm×155 mm) was placed and was weakly melt-adhered thereto for 1.5 seconds using a metal mold heated to a temperature of 150° C. to thereby prepare two pieces of cyclic polyolefin films (A and B) to which small film pieces had been melt-adhered.

After being subjected to γ-ray sterilization, samples were cut into test pieces of a size of (15 mm×50 mm), and were measured for their T-peel strengths to peel the small pieces of film from the film B using a universal tester (Instron). The T-peel strengths were also measured after the samples were stored at 60° C. for one week, three weeks and 7 weeks. The results were as shown in Table 1.

The T-peel strength between the film A and the small pieces of film (just after the preparation) was 15 N/15 mm. TABLE 1 T-peel strength (N/15 mm) LDPE/r-PP Just after Example (weight ratio) preparation 60° C. × 1 W 60° C. × 3 W 60° C. × 7 W 1 70/30 2.2 1.3 1.3 0.9 2 50/50 2.1 1.5 1.0 1.0 3 30/70 0.9 0.8 0.6 0.6

EXAMPLES 4 TO 6

A cyclic polyolefin (trade name: Zeonor manufactured by Zeon Corp.) was extruded at 250° C. to make a film A (60 μm). On this film A (100 mm×155 mm), a small piece of film made of a blend of a low-density polyethylene (density: 0.926 g/cm³, trade name: UBE Polyethylene manufactured by Ube-Maruzen Polyethylene Co.) and a propylene/α-olefin copolymer (Tm 135° C., trade name: Novatec PP manufactured by Japan Polypropylene Co.) (weight ratios of mixture, 70/30, 50/50, 30/70, 60 mm×30 mm) was placed, and was strongly melt-adhered thereto for 2 seconds using a metal mold heated at a temperature of 180° C. Next, on the above small piece of film, another cyclic polyolefin film B (100 mm×155 mm) was placed and was weakly melt-adhered thereto for 1.5 seconds using a metal mold heated at a temperature of 155° C. to thereby prepare two pieces of cyclic polyolefin films (A and B) to which the small piece of film had been melt-adhered.

After being subjected to γ-ray sterilization, samples were cut into test pieces of a size (15 mm×50 mm), and were measured for their T-peel strengths to peel the small piece of film from the film B using a universal tester (Instron). The T-peel strengths were also measured after the samples were preserved at 60° C. for one week, three weeks and 7 weeks. The results were as shown in Table 2. TABLE 2 T-peel strength (N/15 mm) LDPE/r-PP Just after Example (weight ratio) preparation 60° C. × 1 W 60° C. × 3 W 60° C. × 7 W 4 70/30 1.6 1.0 1.0 0.6 5 50/50 1.9 1.5 0.7 0.9 6 30/70 0.6 0.6 0.6 0.6

COMPARATIVE EXAMPLES 1 TO 6

Samples were prepared using small pieces of film as shown in Table 3 instead of using the small piece of film used in Example 1, and by melt-adhering two pieces of cyclic polyolefin films to the small pieces of film in the same manner as in Example 1. Table 3 shows T-peel strengths between the film B and the small pieces of film. In Table 3, the abbreviations have the following meanings:

-   -   LDPE(a): Low-density polyethylene having a density of 0.922         g/cm³, trade name: Petrothene manufactured by Toso Co.     -   LDPE(b): Low-density polyethylene having a density of 0.926         g/cm³, trade name: UBE Polyethylene manufactured by Ube-Maruzen         Polyethylene Co.     -   LLDPE: Straight-chain (linear) low-density polyethylene     -   r-PP: Propylene/α-olefin copolymer

h-PP: Polypropylene homopolymer TABLE 3 T-peel strength (N/15 mm) Composition Just after Comparative Example Polymer (weight ratio) preparation 60° C. × 1 W 60° C. × 3 W 60° C. × 7 W 1 LDPE (a) 100 2.6 0.3 0.2 N.D. 2 LDPE (b) 100 1.0 0.4 0.2 N.D. 3 LLDPE/r-PP 70/30 70.1 N.D. N.D. N.D. 4 LLDPE/r-PP 30/70 33.3 N.D. N.D. N.D. 5 LDPE (a)/h-PP 70/30 0.2 N.D. N.D. N.D. 6 LDPE (a)/h-PP 30/70 0.2 N.D. N.D. N.D.

COMPARATIVE EXAMPLES 7 TO 9

Samples were prepared using small pieces of film as shown in Table 4 instead of using the small piece of film used in Example 1, and by melt-adhering two pieces of cyclic polyolefin films to the films in the same manner as in Example 1. Table 4 shows T-peel strengths between the film B and the small pieces of film. In Table 4, the abbreviations have the following meanings:

-   -   LDPE(a): Low-density polyethylene having a density of 0.922         g/cm³, trade name: Petrothene manufactured by Toso Co.

COP: Cyclic polyolefin TABLE 4 T-peel strength (N/15 mm) Composition Just after Comparative Example Polymer (weight ratio) preparation 60° C. × 1 W 60° C. × 3 W 60° C. × 7 W 7 LDPE/COP 70/30 1.3 0.3 0.2 N.D. 8 LDPE/COP 80/20 1.4 0.3 0.3 N.D. 9 LDPE/COP 60/40 1.6 0.4 0.3 N.D.

As will be obvious from Tables 1 to 4, the small pieces of film using a blend of low-density polyethylene and the propylene/α-olefin copolymer can maintain easily peelable sealing even after being stored at 60° C. for 7 weeks.

EXAMPLE 7

A cyclic polyolefin (trade name: Zeonor, manufactured by Zeon Corp.) was extruded together with a medium-density polyethylene (density of 0.938) using a co-extruder at 250° C. to prepare a two-layer film (former 30 μm, latter 20 μm). A polyethylene terephthalate film (manufactured by Mitsubishi Kagaku Co., 12 μm thick) and a medium-density polyethylene film (density of 0.938, 40 μm thick) were successively laminated on the medium-density polyethylene layer of the two-layer film via a polyolefin-type adhesive resin to prepare a four-layer film (front film).

Next, a cyclic polyolefin (trade name: Zeonor manufactured by Zeon Corp.) was extruded together with the medium-density polyethylene (density of 0.938) using the co-extruder at 250° C. to prepare a two-layer film (former 30 μm, latter 20 μm) Separately, an aluminum foil (20 μm thick manufactured by Sun Aluminum Co.) and a polyethylene terephthalate film (16 μm thick manufactured by Toyobo Co.) were laminated using a polyurethane-type adhesive (manufactured by Takeda Pharmaceutical Co.) to obtain a two-layer laminated body. On the medium-density polyethylene layer of the above two-layer film, the aluminum foil of the two-layer laminated body was laminated via a polyolefin-type adhesive resin to prepare a four-layer film (rear film).

The above four-layer film (front film) of a square shape and the above four-layer film (rear film) of a square shape were overlaid on one another, a small piece of film made of a blend of low-density polyethylene and propylene/α-olefin copolymer (weight ratio of mixture, 70/30) was held between the ends thereof, and one surface thereof was strongly melt-adhered and the other surface was weakly melt-adhered at an upper metal mold temperature of 80° C., a lower metal mold temperature of 140° C. and a pressure of 0.3 MPa. Both ends of the base end side were strongly melt-adhered together at 170° C. and a pressure of 0.3 MPa to form a medicine chamber (bag-like container 140 mm high and 115 mm wide for the medicament). A non-melt-adhered portion without the above film was left on the base end side of the two films.

The medicine chamber in the form of a bag was subjected the γ-ray sterilization, aseptically filled with 1.0 g of a powdery antibiotic through an end thereof, and the end was strongly melt-adhered together to form a bag-like container.

A small piece of film made of a blend of low-density polyethylene and propylene/α-olefin copolymer (weight ratio of mixture: 70/30) was inserted in an upper end of a polyethylene tubular film that was opened at both ends, the tubular film was weakly melt-adhered to the above small piece of film to thereby form a partition portion (weakly melt-adhered seal portion), and the front and back wall portions, except the partition portion of the tubular film, were strongly melt-adhered so as not to be peeled off on both the right and left sides thereof. Subsequently, a connection port was inserted in the lower end of the tubular film and was strongly melt-adhered together so as not to be peeled off, and the remaining opening portion at the lower end of the tubular film was strongly melt-adhered together so as not to be peeled off in order to form a second chamber.

The non-melt-adhered portions of the medicine chamber were widely opened downward, the upper end of the second chamber was inserted between the two non-melt-adhered portions of the medicine chamber from the lower side, which were then heat-melt-adhered together to connect the two chambers integrally together.

This application claims priority based on Japanese Patent Application No. 2005-264383, filed Sep. 12, 2005, which is incorporated herein by reference. 

1. A multi-chamber container having a plurality of chambers formed of a film of which at least an innermost layer is a cyclic polyolefin, wherein one chamber and another chamber are partitioned by a partitioning wall, and said partitioning wall comprises an easily peelable seal layer that contains a low-density polyethylene and a propylene/α-olefin copolymer.
 2. The multi-chamber container according to claim 1, wherein said easily peelable seal layer is a composition containing a low-density polyethylene and a propylene/α-olefin copolymer at a weight ratio of 80:20 to 20:80.
 3. The multi-chamber container according to claim 1, wherein said easily peelable seal layer is an easily peelable single-layer film or an easily peelable multi-layered film having an easily peelable layer on the surface thereof.
 4. The multi-chamber container according to claim 1, wherein said partition wall includes a weakly melt-adhered seal portion comprising said easily peelable seal layer and a strongly melt-adhered seal portion.
 5. The multi-chamber container according to claim 1, wherein the film constituting said plurality of chambers is a multi-layered film including a first layer of a cyclic polyolefin which is the innermost layer and a second layer of a linear polyolefin adjacent to said layer.
 6. The multi-chamber container according to claim 5, wherein the film constituting said plurality of chambers further has a gas-barrier layer and/or a printable layer on the second layer of said linear polyolefin.
 7. The multi-chamber container according to claim 6, wherein said gas-barrier layer is a metal foil, a metal-deposited layer or an inorganic material-deposited layer.
 8. The multi-chamber container according to claim 6, wherein said printable layer is a polyester layer or a polyester layer having an inorganic material-deposited thin film thereon.
 9. The multi-chamber container according to claim 1, wherein said plurality of chambers includes one for containing a liquid agent and one for containing a medicine.
 10. The multi-chamber container according to claim 1, wherein said multi-chamber container includes a pair of partition walls facing the ends on one of two chambers, an end of the other chamber is inserted and is melt-adhered between the partition walls, and the two chambers are partitioned by said partition walls. 